Discrimination between poultry eggs (hereinafter “eggs”) on the basis of some observable quality is a well-known and long-used practice in the poultry industry. “Candling” is a common name for one such technique, a term which has its roots in the original practice of inspecting an egg using the light from a candle. Although egg shells appear opaque under most lighting conditions, eggs are actually somewhat translucent. Accordingly, when placed in front of a light, the contents of an egg can be observed.
In poultry hatcheries, one purpose of candling eggs is to identify and then segregate live eggs (i.e., eggs which are to be hatched to live poultry) from non-live eggs (e.g., clear eggs, dead eggs, rotted eggs, empty eggs, etc.). U.S. Pat. Nos. 4,955,728 and 4,914,672, both to Hebrank, describe a candling apparatus that uses infrared detectors and the infrared radiation emitted from an egg to identify live eggs. U.S. Pat. No. 4,671,652 to van Asselt et al. describes a candling apparatus in which a plurality of light sources and corresponding light detectors are mounted in an array, and wherein eggs are passed between the light sources and the light detectors to identify live eggs.
Once identified, live avian eggs may be treated with medications, nutrients, hormones and/or other beneficial substances while the embryos are still in the egg (i.e., in ovo). In ovo injections of various substances into avian eggs have been employed to decrease post-hatch morbidity and mortality rates, increase the potential growth rates or eventual size of the resulting bird, and even to influence the gender determination of the embryo. Injection of vaccines into live eggs have been effectively employed to immunize birds in ovo. It is further desirable in the poultry industry to manipulate an embryo in ovo to introduce foreign nucleic acid molecules (i.e., to create a transgenic bird) or to introduce foreign cells (i.e., to create a chimeric bird) into the developing embryo.
In ovo injection of a virus may be utilized to propagate the particular virus for use in preparation of vaccines. Examples of substances that have been used for, or proposed for, in ovo injection include vaccines, antibiotics and vitamins. Examples of in ovo treatment substances and methods of in ovo injection are described in U.S. Pat. No. 4,458,630 to Sharma et al. and U.S. Pat. No. 5,028,421 to Fredericksen et al.
Improved methods of injecting eggs containing an embryo may be used to remove samples from eggs, including embryonic and extra-embryonic materials. Further, for other applications it may be desirable to insert a sensing device inside an egg containing an embryo to collect information therefrom, for example, as described in U.S. Pat. No. 6,244,214 to Hebrank, which is incorporated herein by reference in its entirety.
In commercial hatcheries, eggs typically are held in setting flats during incubation. At a selected time, typically on the eighteenth day of incubation, the eggs are removed from an incubator. Unfit eggs (namely, dead eggs, rotted eggs, empties, and clear eggs) are identified and removed, live eggs are treated (e.g., inoculated) and then transferred to hatching baskets.
In hatchery management, it may be desirable to separate birds based upon various characteristics, such as gender, diseases, genetic traits, etc. For example, it may be desirable to inoculate male birds with a particular vaccine and inoculate female birds with a different vaccine. Sex separation of birds at hatch may be important for other reasons as well. For example, turkeys are conventionally segregated by sex because of the difference in growth rate and nutritional requirements of male and female turkeys. In the layer or table egg industry, it is desirable to keep only females. In the broiler industry, it is desirable to segregate birds based on sex to gain feed efficiencies, improve processing uniformity, and reduce production costs.
Unfortunately, conventional methods of sexing birds may be expensive, labor intensive, time consuming, and typically require trained persons with specialized skills. Conventional methods of sexing birds include feather sexing, vent sexing, and DNA or blood sexing. About three-thousand (3,000) chicks can be feather-sexed per hour at a cost of about 0.7 to 2.5 cents per chick. About fifteen hundred (1,500) chicks can be vent-sexed per hour at a cost of about 3.6 to 4.8 cents per chick. DNA or blood sexing is performed by analyzing a small sample of blood collected from a bird.
It would be desirable to identify the sex of birds, as well as other characteristics of birds, prior to hatching. Pre-hatch sex identification could reduce costs significantly for various members of the poultry industry. Although conventional candling techniques can discriminate somewhat effectively between live and non-live eggs, these conventional candling techniques may not be able to reliably determine gender and other characteristics of unhatched birds.